1. Field of the Invention
The present invention relates to a headrest for use on an automotive seat and a method for forming the same. More particularly, the invention is directed to a headrest of the fore-and-aft inclinable type having an inclining mechanism incorporated therein, wherein the headrest can be inclined forwardly and backwardly of the seat via the inclining mechanism, and also directed to a method for forming that particular type of headrest under a foaming process comprising the steps of injecting a liquid base foaming material into the hollow interior of a trim cover assembly of a predetermined headrest shape, in which the inclining mechanism and a headrest frame with headrest stays have been installed, and curing the injected liquid base foaming material to create and fill a foam padding in the trim cover assembly, integrally together with the inclining mechanism and headrest frame.
2. Description of Prior Art
Among various sorts of headrest for use on an automotive seat, there has been known the fore-and-aft inclinable type of headrest wherein the headrest body thereof can be inclined forwardly and backwardly relative to a headrest stay or seat back of the seat, with a view to allowing a passenger on a rear seat to attain a wide view in the forward direction of automobile by inclining the headrest body forwardly of a front seat on which the headrest is supported via its headrest stay.
This inclining of headrest is adjustably effected via an inclination mechanism incorporated in the headrest body, which is typically composed of a ratchet device for instance. Conventionally, for that purpose, the construction of headrest has been based on a simple layer covering process such that the inclining mechanism is surrounded by a metallic casing layer, then this metallic casing layer is entirely covered with a preformed foam padding layer of a predetermined headrest shape, and finally, the foam padding layer is entirely covered with a there-dimensional covering layer of a given headrest configuration (i.e. a three-dimensional bag-shaped trim cover assembly preformed by sewing together separate cover sections). In most cases, an opening is perforated coaxially through all those layers in order to allow for insertion of headrest frame and headrest stay or entry of worker's hands therethrough into the hollow interior defined therein to form a resulting headrest. Hence, there has been the necessity for a worker to close such opening by means of a particular closing element such as a fastener of Velcro or loop-and-hook fastening type, which renders troublesome the headrest assembling steps on the worker's part and requires a number of parts and lengthy period of time involved. Further, such mere juxtaposition of the three separate layers with one another in this prior-art headrest gives a rise to the drawback that an external force given by a user to the headrest for its inclination purpose causes the top covering layer or trim cover assembly to dislocate from a given position relative to the foam padding layer, resulting in creation of objectionable creases or deformed spots on the outer aesthetic appearance of headrest.
Solution to this problem can be found from such a foaming process as suggested in the Japanese Laid-Open Patent Pub. No. 8-141232, according to which a headrest frame is provided, which surrounds and incorporates a headrest inclination mechanism therewithin and, in assembly, the frame is subjected to foaming with a three-dimensional covering member so as to create a foam padding integrally with and between the headrest frame and covering member. The headrest frame of this prior art is provided with a projected portion with an elongated hole through which a headrest stay movably passes, thereby permitting the headrest frame or headrest body to be inclined fore-and-aft with respect to the headrest stay. The projected portion has a radially extending flange portion formed at its end. The covering member is, therefore, formed with an elongated hole corresponding to that of the projected portion of headrest frame. Prior to a foaming process, a local part of the covering member adjacent such elongated hole is retained between aforesaid radially extending flange portion and an inner wall of foaming die, so that a liquid base foaming material to be injected in the foaming die is prevented against leakage therethrough.
However, even this prior-art headrest structure and foaming procedures have been found defective in terms of incomplete sealing because the flange portion and inner wall of foaming die are simply contacted with each other on a flat plane to retain therebetween the local part of covering member adjacent the elongated hole, which remains of a high likelihood that liquid base foaming material will be invaded or leaked therethrough. Moreover, such arrangement and steps cause a difficulty in quickly locating the headrest frame at a given position within the foaming die in order to insure avoiding the leakage problem.